As well as the long-term signal, there's been a jump in the snow row for 11th January. There does seem to be a trend for the SW flank of the strong Atlantic trough to reach a little further SW, providing a brief window for a snow showers in the unstable airflow.

That's about the best we can do as far as the next 10 days is concerned.

There still seems to be problems with the MJO data being displayed on the NOAA site at the moment... stuck with the ECM and UKM output from two days ago, while the GEFS output has gone AWOL.

Obviously they're still running (else we'd have critical data shortages), just not visible.

Ensembles analysis. 324hr that is 18th January.

High pressure close to UK (cP): IIIIII

Total: 6

High pressure close to UK (inversion): IIII

Total: 4

Mid-atlantic High (cP/A): III

Total: 3

Greenland high (cP/A): III

Total: 3

Azors high (mT): IIII

Total: 4

Icelandic Vortex (mT): II

Total 2

Hope index = 6+4+3+3/6+4+3+3+4+2 = 72%

Hope index continues to rise, as the models strongly trend towards the cold spell. However Gandalf is right, the nature of the cold spell being suggested is closer to what we had before the new year than anything desperately cold and snowy. The dominating solution now is HP close to the UK with a weak easterly feed, Kent is the favoured spot to see snow now. 

However there are still some solutions that invoke a slicer low and a retrogression to convert the very weak scandi into a greenie.

Since we don't get the full EPS unfortunately I have to do this. Nevertheless

So I have used a very crude method to determine whether the EPS are zonal or blocked, if they are zonal the air-mass temperature variation is more significant than the diurnal temp variation, wheras in blocked conditions the reverse is true, the exception to this rule is when the temperature is both cold and flat which indicates inversion conditions and is categorized as blocked.

Anyway crude as it may be it does give some indication of the transition period which is late on the 12th at the earliest or early on the 17th at the latest, and probably somewhere around the 15th. 

By the 17th we have the cold spell with the mean dropping below 5C, and most of the EPS runs keep us in blocked conditions with very few returning to zonal. 

For the GEFS similar chart.

Given we have full ensembles and upper air temp graphs this is hardly necessary, however I did it so a direct fair comparison can be done to the EPS. It is largelly similar, although the GEFS seems less inclined to have all its members go blocked, although most do by the 16th/17th. The date is similar to that of the EPS

If one were to make a bet on the start of the cold spell, then the 16/17th + a few days lag is a good way to go.

Q have a browse in the media thread. There is no impending cold spell according to MetO and after many burnt offerings from the NWP I know who I believe.

I don't know what to say, its not what I see on the EPS and GEFS, the metoffice models might suggest something completely different, but then I don't have access to those models so can't comment.

GFS12z says shows why it pays to be cautious:

IOIWA

It could be that the model output that we have access to is perhaps barking up the wrong tree wrt what happens later in January, but there again the Met Office themselves have occasionally got longer range forecasts wrong as well.

Perhaps if the GFS sticks to its guns and the likes of ECM et al get on board as the second half of January gets nearer, we may see the MetO alter their outlook somewhat. Still a long way to go before we even reach mid-January however.

As Brian has highlighted, a really crap GFS 12z run. Although i guess its just another take on the possible change of pattern, or at least a breather before the crap returns.

Yes a very long way to go if the 12Z GFS OPs are to be believed. Another swing away from a cold spell - we await the suite.

12z GFSP is also poor.

http://www.theweatheroutlook.com/twodata/datmdlout.aspx

Zonality doesn't skip a beat on the GFSP.

I expect the Met Office will be right, as usual, with the best us getting being a toppler or a UK high. GFS in leading us up the garden path with deep FI cold charts shocker.

Actually the GFSP 12z op run has a heavy snow event for the south on Sunday 18th followed by disruption of the Atlantic trough as heights rise to the NE. It then blows that away, but this is far-FI we're talking about so it has little significance aside from the continued signal for a more amplified pattern.

GFS also has the more amplified pattern but it leads to a UK/Europe block, cold at the surface in the UK (continental feed, first from the east then more south but circling around from the east).

It's all rather finely balanced and we know how little faith we can place in GFS, or indeed any model, beyond about 5 days range, particularly when trying to handle amplified patterns.

Still no ECM, UKM or JMA MJO updates to work with so still unable to comment on the likelihood of the amplification being upgraded or downgraded - but the Met Office outlooks suggest that at least one of those models remains less keen; I'm fairly sure they place little faith in the GEFS and CFS output unless there is a strong indication that they should do otherwise.

Anyway, I hope I've successfully balanced out the blunt, one-sided one-liner posts for the time being.

Edit: but I do agree that high pressure dominating across the UK seems to be the most prominent signal today and is the current 'safe bet'.

That'd be a "bank" run. Widespread snow:

http://modeles.meteociel.fr/modeles/gfsp/runs/2015010512/gfs-2-276.png?12

followed by more snow:

http://modeles.meteociel.fr/modeles/gfsp/runs/2015010512/gfs-2-300.png?12

I haven't seen too many one-liner one-sided posts today, James, unless I'm looking at the wrong forum?

The control goes with the OP but some of the members take the high further North.

Pert 4 the pick for me of the 12Z OP ENS.
At least we're seeing some candy, although ultimately it is likely to be unavailable for consumption.

GEFS12z showing the cool down and then a possible warming trend towards the end.

I know GFSP is taking over GFS on the 14th but is there any verification stats to know how well the model has performed?

Will be interesting to see how it performs vs GFS as there are subtle but vital differences within the high resolution time frames.

Here you go Mike:

http://www.emc.ncep.noaa.gov/gmb/STATS/html/new_acz5.html

In the NH the existing GFS is outperforming it. 

Thanks Brian

Interesting. For the period 21st Dec to Christmas, it was shockingly bad... and the stats have confirmed what I suspected that the current GFS has performed slightly better (since I have been paying more attention to the models again).

A step back for coldies as GEFS at 360h  has virtually no cold members as opposed to 50% at 0h.HP seems to be headed for azores or over  uk which chimes with  with metos more settled option (but not cold) late in January.